Cyprinid herpesvirus II (CyHV-2), also known as Herpesviral haematopoietic necrosis virus (HVHN) or Goldfish haematopoietic necrosis virus (GFHNV) is classified as a member of the genus Cyprinivirus, the family Alloherpesviridae, together with the other two Herpesviruses of Cyprinid fish family, CyHV-1 (Carp pox) and CyHV-3 (Koi herpesvirus, KHV). CyHV-2 was first reported in 1995 to cause huge economic losses to goldfish culture in western Japan from 1992 to 1993 and the mortality for the infected goldfish was as high as 100%, followed by reports of a successive outbreaks of such disease in other countries and regions. In the spring of 1997, a large number of deaths occur in the US west coast for circulating aquaculture juvenile goldfishes, and the mortality was up to more than 80%, which was confirmed later by CyHV-2 infection. The international trade of ornamental fish is largely contributed to the global spread of the disease, and soon afterwards, the disease outbreaks successively in cultured goldfishes in Taiwan, Australia and the United Kingdom. In 2011, Hungary reported that CyHV-2 infection was also found in the cultured Carassius auratus gibelio. Since 2009, haematopoietic necrosis in crucian carp caused by CyHV-2 outbreaks in Jiangsu Province, China's major crucian carp culture areas. By mid-June 2012, an area of over 100,000 acres in the regions as Sheyang, Dafeng, Yandu, Baoying, Gaoyou, Xinghua, Hongze, Chuzhou in Jiangsu Province occurred disease, the mortality in the diseased ponds were up to 90%, and the economic losses has reached several hundred of millions. Meanwhile, in Hubei, Hunan, Jiangxi and Heilongjiang Provinces, CyHV-2 was also detected in the bodies of affected crucian carps. The virus has strong infectiousness and high mortality, causes huge economic losses to crucian carp and goldfish aquaculture, and seriously threatens to the development of crucian carp and goldfish aquaculture.
Cell culture and separation technique is the most accurate method in the diagnosis of virus disease, and it is usually recommended by the World Organization for Animal Health (OIE) as the preferred method for the detection of fish virus. However it has been found very difficult to proliferate CyHV-2 in common cell lines for the isolation of fish virus. Fathead minnow (FHM) cells, epithelioma popuasum cuprini (EPC) cells, eel kidney (EK-1) cells, chinook salmon embryo (CHSE-214) cells, rainbow trout gonad (RTG-2) cells and tilapia ovary (T0-2) cells are not sensitive to CyHV-2, only koi fin 1 (KF-1) cells can produce cytopathic effect (CPE). However, after three passages of the virus in KF-1 cells, CPE disappeared and no viral nucleic acid can be detected. Due to the lack of CyHV-2-sensitive cell lines, the study of CyHV-2 is limited, thus the establishment of a CyHV-2-sensitive cell line and study of its biological characteristics are of great significance to consecutive passage amplified culture of CyHV-2 and deep study of the characteristics of the virus. The present invention establishes a sensitive cell line GiCB for isolation and culture of cyprinid herpesvirus II. The application of the cell line includes but not limited to: development of physical and chemical properties, morphogenesis, virus infection approach, infection mechanism of cyprinid herpesvirus II and other fish viruses at molecular level; preparation, screen or evaluation of fish antiviral drugs.